Fluid pressure developing units



Jan. 3, 1967 I H. (s. ORAM 3,295,457

' FLUID PRESSURE DEVELOPING UNITS Filed March a, 19 64 s Sheets-Sheetl Jan. 3, 1967 H. G. ORAM FLUID PRESSURE DEVELOPING UNITS 6 Sheets-Sheet 2 Filed March 6, 1964 e 4 e m N\ a I, i AMI. S. mm Q? @N 0 9 0m NN 1 i W I. R e: F K R a i ll voo'qfi I .srl '6' l I m 5 0m 3 mm f 3 mw ll w /n 2 q Q IN Q S UM .3) 5m Jan. 3, 1967 H. G. ORAM FLUID PRESSURE DEVELOPING UNITS e Sheets-Sheet s Filed March 6, 1964 1 6 H. G. oRAM 3,295,457-

FLUID PRESSURE DEVELOPING UNITS 17 M W Am .Br wow/flaw Jan. 3, 1967 H. G. ORAM 7 3,295,457

FLUID PRESSURE DEVELOPING UNITS 10W M .21/ aldwm a? G. ORAM FLUID PRESSURE DEVELOPING UNITS Jan. 3, 1967 6 Sheets-Sheet 6 Filed March 6. 1964 United States Patent 3,295,457 FLUID PRESSURE DEVELOPING UNITS Harold George Gram, 285 Hangleton Road, Hove, Sussex, England Filed Mar. 6, 1964, Ser. No. 349,849 9 Claims. (Cl. 103-118) This invention relates to fluid pressure developing units and seeks to provide a unitary construction in which piston and cylinder units are used to create the fluid pressure and hence a flow of fluid, and in which the prime mover for the unit surrounds said piston and cylinder units.

A unit arranged in the above manner provides a compact space saving and low cost assembly since there is no necessity for a separate prime mover, nor is space wasted by the conventional requirement of a coupling assembly for connecting the output shaft of a separate prime mover to the input shaft of a conventional pump.

According to the present invention the pressure developing unit comprises an electric motor, the rotor of which houses a plurality of cylinders, a piston in each cylinder, each piston having one end projecting from one end of the cylinder, said projecting ends of said pistons, or means secured thereto, being constrained to be maintained in sliding relationship with a thrust plate, and means for supporting the thrust plate in an inclined relationship with respect to the rotational axis of the rotor such that as the rotor rotates the pistons are caused to reciprocate in their cylinders, the open end of each cylinder being connected, on rotation of the rotor, in sequence to an inlet port and an outlet port of the unit.

The unit may include a valve plate having two arcuate shaped ports therein, said ports defining between them a circle except for the blank space or land between the ends of adjacent ports. The open ends of the cylinders, as the rotor rotates, are aligned with each of these arcuate shaped ports in turn, one of said arcuate shaped ports being connected to said inlet port and the other of said arcuate shaped ports being connected to said outlet port.

The thrust plate may be stationary and so positioned that its nearest and furthest points from the rotor lie on a line that is in line with, or substantially in line with a centre line of the valve plate passing through the two blank spaces or lands thereon.

In a modified construction the thrust plate may be controlled such that it can be rotated or rocked about the axis of the rotor, whilst maintaining its fixed inclination thereto, and so cause said centre line on the thrust plate to be moved out of alignment with said centre line on the valve plate, such an arrangement enabling the output of the unit to be controlled and if the thrust late is rotated sufliciently the output of the unit can thus be reversed.

In a further arrangement the thrust plate can be controlled such that it can be caused to pivot about an axis normal to, or substantially normal to the rotor axis to vary its inclination with respect to the rotor axis and thus control the output of the unit.

The rotor is preferably of the wound or squirrel cage type with the windings or the bars of the squirrel cage embedded or wrapped in insulation and housed in slots or grooves formed in the laminations.

The cylinders of the cylinder and piston units may be in the form of sleeves inserted into bores formed in said rotor laminations or said cylinders may be assembled in a unit constructed separately from the rotor and which is subsequently fitted into the rotor.

The unit may employ a rotating or a non-rotating shaft.

In order that the invention may be clearly understood reference will now be made to the accompanying drawings, in which:

FIG. 1 is a side elevation, in cross section, of a first embodiment of a fluid pressure unit according to the prescut invention, only one piston and cylinder unit being shown for reasons of clarity;

FIG. 2 is a side elevation, in cross section, of a second construction;

FIG. 3 is a side elevation, in cross section, of a third construction;

FIG. 4 is a side elevation, in cross section, of a fourth construction;

FIG. 5 is a side elevation, in cross section, of a fifth construction; and a FIG. 6 is a side elevation, in cross section, of a sixth construction.

Referring first to FIG. 1 it will be seen that there is provided a housing 1 having end cover plates 2 and 3, the cover plates being secured to the housing 1 by means of bolts not shown.

The housing 1 serves as a means for supporting the stator and windings 4 of an electric motor whilst the cover plates 2 and 3 serve as means for supporting the ends of a non-rotating shaft 5 on which the rotor 6 of the electric motor is rotatably mounted. The rotor 6 is of laminated construction, the laminations being mounted on a sleeve 7 that seals the inner circumference of the laminations of the rotor 6 and also acts as a housing for needle or roller bearings 8 mounted between thesleeve 7 and the shaft 5 at both ends of the sleeve 7.

The rotor 3 may be of thewound or squirrel cage type with the windings or the bars of the squirrel cage embedded or wrapped in insulation andhoused in slots or grooves formed in the laminations but for reasons'of clarity such windings or bars have been omitted from the drawings.

The rotor 6 is formed with a number of bores 9, only one of which is shown in the drawing, all parallel or substantially parallel to the shaft 5 and equally spaced therefrom. The bores 9 may be uneven in number, for example 7, 9, or 11, although 9 is preferred, each bore being equally spaced from the next one.

Withineach bore 9 is a sleeve 10 acting as a cylinder for a piston 11 therein and also serving to render said bores 9 fluid tight, the sleeves 10 being, if desired, axially slidable in the bores 9. V

The rotor 6 is clamped between a cylinder port plate 12 at the end facing the cover plate 2 and a pressure plate 13 at the end facing the cover plate 3, the sleeves 10 projecting from the laminations of the rotor 6 and into recesses 14, 15 in the cylinder port plate 12 and the pressure plate 13 respectively to hold these plates 12 and 13 against rotation relatively to the rotor 6.

The recesses 14 in the cylinder port plate 12 are a sliding fit on the sleeves 10 and each recess 14 includes a liquid tight seal 16 between it and the outer circumference of the sleeve 10. Each recess 14 also terminates in the opening 17 extending through the cylinder port plate 12 to an arcuate shaped port 18 on the other face of the cylinder port plate 12, there being one arcuate shaped port 18 for each recess 14.

Mounted on the shaft 5, between the cylinder port plate 12 and a boss 19 extending axially inwardly from the cover plate 2, is a valve plate 20, the valve plate 20 being correctly but non-rotatably mounted on the fixed shaft 5 by means of a key 21 extending into aligned grooves in the shaft 5 and the valve plate 20. The key 21 also extends into a groove in the boss 19 to hold the shaft 5 against rotation. The valve plate 20 is formed with two arcuate shaped ports, only part of one of which is indicated at 22, the mean radius of said ports about the axis of the shaft 5 being equal to the mean radius of the plurality of the arcuate shaped ports 18 about the same axis. The purpose of the two arcuate shaped ports in the valve plate 20 is to properly phase fluid from the sleeves to suction and discharge ports in the cover 2, only one of these suction and discharge ports being illustrated in the drawing namely the discharge port 23. For this purpose the arcuate shaped ports in the valve plate each subtend an angle that is somewhat less than 180. The valve plate 20 also acts as a wearing surface for the cylinder port plate 12.

The pressure plate 13 is a sliding fit on the sleeves 10.

Each of the pistons 11 has an end 24 extending outwardly through the pressure plate 13 said end 24 being spherical in shape and having swaged thereon a shoe 25 such that said shoe 25 .is capable of rotating on the spherical head. Each of the shoes 25 is formed with an end face that is in sliding contacting an annular shaped thrust plate 26, the thrust plate 26 being inclined to the axis of the shaft 5 in the manner shown. The end cover 3 has an inwardly directed boss 27 that is suitably shaped to support the annular thrust plate 26 in its inclined setting.

The pressure plate 13 is formed with a concentric cylndrical projection 28 extending towards the boss 27, said projection 28 terminating in a semi spherically shaped surface 29 on which is rotatably mounted an annular shaped plate 30, the opern'ng in the annular shaped plate 30 being shaped to match the spherical contours of the surface 29. The plate 30 is formed with a number of holes, one for each shoe 25, and the shoes project into these holes. Each shoe 25 is formed with an annular flange 25A that is trapped between the thrust plate 26 and the plate 30 to prevent displacement of the shoe away from the thrust plate 26.

Each of the pistons 11 has an axially extending bore therethrough, said bore extending through the spherical end 24 of the piston so that any fluid pressure created in a sleeve 10 can be transmitted to an orifice 31 in the associated shoe 25, said orifice leading to a circular recess 32 in that face of the shoe 25 that is in sliding contact with the annular thrust plate 26.

The shaft 5 has a blind and axially extending bore 33 therein, said bore commencing at that end of the shaft 5 that is accommodated in the boss 19 and terminating in that part of the shaft 5 that is within the cylindrical extension 28. The open end of the shaft 5 is closed by the boss 19 but this end of the shaft 5 is formed with a slot 34 in its side wall that leads into an annular cavity 35 in the boss 19, said cavity 35 surrounding the shaft 5 and being connected by a passage 36 to the discharge port 23.

At the blind end of the bore 33 are two radially extending passages 37, 38. Passage 37 leads into a chamber 39 defined by an annular space between the inner surface of the cylindrical extension 28 and the outer surface of the shaft 5 within said extension. The chamber 39 is closed at one end by a bearing surface 40 between the shaft 5 and the cylindrical extension 28 and at its other end by a bearing surface 41 between the shaft 5 and the pressure plate 13. The passage 38 leads to an annular recess on the inner face of the bearing surface 41.

The unit illustrated includes seals 42in the cover plates 2 and 3 such that these cover plates can make a fluid tight connection with the housing 1.

A closure plate'43 is bolted to the cover plate 3, there being sealing means 44 between the closure plate 43 and the cover plate 3. The plate 43, when removed, exposes one end of the shaft 5.

Plug 45 is provided for sealing purposes. Passage 20' may be provided in the valve plate 20 to permit fluid pressure equalisation between chambers situated at the terminations of the passage.

Operation of the fluid pressure unit shown in FIG. 1

When the stator 4 is energized by an electrical supply the rotor 6 is caused to rotate on the bearings 8 about the shaft 5, the shaft 5 being held stationary against rotation by the key 21 in the boss 19. The rotation of the rotor 6, and therewith the piston heads 24, causes the shoes 25 to travel in an orbited path around the shaft 5 in a plane parallel to that defined by the thrust plate 26.

This movement of the shoes 25 causes the pistons 11 to be reciprocated in the sleeves 10, the plate 30 preventing the shoes 25 from pulling away from the thrust plate 26. Commencing with a piston 11 in its innermost position in its sleeve 10 as shown in the drawing, the piston 11 will commence to be Withdrawn from its sleeve 10 on further rotation of the rotor 6. At this stage the ports 17, 18, moving with the sleeve 10 about the shaft 5 are brought into alignment with the first of the two arcuate ports in the valve plate 20 said first arcuate port being permanently connected to the suction port (not shown) in the cover 2. Fluid is thus sucked through the suction port in the cover plate 2, into the first arcuate port in the valve plate 20 and thence through the ports 18, 17 in the cylinder port plate 12 into the sleeve 10. The first arcuate port in the valve plate 20 is sufficiently long to permit this drawing in of fluid to continue until the sleeve 10 is approximately at its top dead-centre position. Thereafter the ports 17, 18 are temporarily substantially sealed by passing over a land or blank space on the valve plate 20 between the two arcuate ports therein, until the ports 17, 20 come into alignment with the second arcuate port 22 in the valve plate 20. At this stage the piston 11 commences its compressive stroke and fluid is then forced to flow out of the sleeve 10 and thence through the ports 17, 18, 22 to the discharge port 23. The second arcuate port 22 in the valve plate 20 being sufficiently long to permit the piston 11 to substantially complete its com pressive stroke :before the ports 17, 18 are temporarily substantially closed by passing over a second land or blank space on the valve plate 20 between the two arcuate ports therein. The ports 17, 18 subsequently come 1nto alignment again with the first arcuate port in the valve plate 20 and the cycle is then repeated.

During each compressive stroke of a piston 11 the fluid pressure generated in a sleeve 10 is transmitted via the bore in the piston to the orifice 31 in its associated shoe 25 and thus to the recess 32 in that face of. the shoe that faces the thrust plate 26 to counteract frictional resistance between the shoe 25 and the thrust plate 26.

Similarly, the fluid pressure in the discharge port 23 is transmitted via the passage 36, the annular cavity 35 and the slot 34 to the bore 33 in the shaft 5. The pressure in the bore 33 is transmitted via the radial passage 37 to the chamber 39 to bias the pressure plate 13 against the rotor 6.

The cross sectional area of the ends of the sleeves 10 in the cylinder port plate 12 is such that pressure acting thereon is sufficient to bias the pressure plate 13 against the annular plate 30 thus insuring correct operation of the shoes 25.

Any distortion, disengagement or misalignment of the valve plate 20 and the cylinder port plate 12 with the plane surface of boss 19 is corrected by pressurized fluid pressing on the inner annular surface or shoulder of the recesses 14 accommodating the sleeves 10, thus bias-ing said cylinder port plate against the plane surface of the valve plate 20.

It will be appreciated that in the above embodiment the throw of the pistons 11 is constant and the unit thus has a constant rate of. output for a given rotational speed.

Referring now to FIG. '2 it will be seen that a second construction of the invention is illustrated in which the annular thrust plate 26 is again supported at a fixed inclination to the shaft 5 of the rotor 6 by the boss 27 on the cover plate 3. This unit, therefore, has a fixed output for .a given speed :as has the unit illustrated in FIG. 1.

The parts that are identical with, or similar to, corresponding parts in FIG. 1 have been identified with reference numbers corresponding with those in FIG. 1 and hence need not be subjected to repeated description.

The essential ditference in the construction illustrated in FIG. 2 is that the pistons 11 now bear directly on a thrust plate 26 that is rotatably supported on roll or ball bearings 46 running in a ringamember 47 supported by the boss 27 in an inclined setting with respect to the rotational axis of the rotor 6. The ring-member 47 has an annular wall 48 extending into the thrust plate 26. The thrust plate may have a castellated surface providing recesses 49, there being one recess for each piston 11 and into which the end of the piston projecting from the rotor extends.

The pistons 11 are main-tinned in engagement with the thrust plate 26 by means of a compression spring 50 Within each sleeve 16, said spring in each sleeve having one end abutting the cylinder port plate 12 and its other end extending into a blind bore in the piston 11.

The shaft 5 is illustrated as being rotatably mounted at one end on needle bearings 51 in the boss 19 of the cover 2, although it will be appreciated that ball or roller bearings could be used. The opposite end of the shaft 5 is rotatably supported by a roller bearing unit 52 housed in a shouldered recess in the boss 27, the roller bearing unit 52 being clamped against the shoulder 53 of said recess by an annular projection 54 on a closure plate 55 bolted to the cover plate 3.

The roller bearing unit 52 is mounted on an enlarged portion 56 of the shaft 5 and this enlarged portion is reduced at its outer end as at 57 to provide a shoulder 58 that abuts against a thrust bearing 59 housed in a recess in the closure plate 55. The enlarged portion 56 of the shaft 5 is formed with a circumscribing groove 60 in which a circlip 61 is retained to provide a means for correctly positioning the bearing 52 on the shaft during assembly.

The shaft 5 includes a second circumscribing groove 62 adjacent the pressure plate 13, and a circlip 63 is housed in the groove 62 to maintain the pressure plate 13 in engagement with the rotor 6 and to hold the sleeves 10 against rearward displacement.

The valve plate is of the same construction as previously described except that it is now held against rotation by means of a pin 64 extending therethrough and into the boss .19 on the cover 2.

Since the shaft 5 in FIG. 2 is rotatable, the needle bearings 8 as described with reference to FIG. 1 :are now dispense-d with and the rotor 6 is now coupled directly to the shaft 5 by means of a key 65 extending into a slot (unnumbered) in the shaft 5 as well as a slot extending along the length of the rotor 6.

The function of the ports in the cylinder port plate 12, in the valve plate 20, and in the cover plate 2 is the same as described with reference to FIG. 1.

Only one sleeve 10 :and piston 11 is illustrated in FIG. 2 for reasons of clarity, there being in practice a plurality of such piston and cylinder units evenly spaced apart and at equal radius from the axis of the shaft 5.

FIG. 3 illustrates a further modification of the invention with parts that have already been described with reference to FIGS. 1 and 2 being identified with the corresponding reference numerals.

This embodiment is somewhat similar to that described with reference to FIG. 2 since the pistons .11 in the rotor 6 are again biased by compression springs 50 against a thrust plate 26, the thrust plate 26 being inclined to the axis of the shaft 5. In this construction, however, the shaft 5 is held stationary by means as described with reference to FIG. 1 as, for example, by means of a key 21 in a slot in the boss 19 extending into a slot in the shaft 5. As in FIG. 1 the rotor is mounted on a sleeve 7 rotating on needle or roller bearings 8 mounted between the sleeve 7 and the shaft 5.

The shaft 5 has a circumscribing groove 66 spaced from the sleeve 7 at a position between the sleeve 7 and the boss 27 of the end cover 3. A circlip 67 in the groove 66 7 and rotor 6 toward the boss 27 when the fluid in the sleeves 10 is subjected to pressure.

Sleeve 10 is restrained from axial displacement towards boss 27 by circlip 166 in a circumsc-ribing groove 161, said circlip abutting rotor 6.

The shaft 5 has one end supported in the boss 19 of the cover plate 2 and its other end supported in the boss 27 of the cover plate 3. Extending through the cover plate 3 and into the bore accommodating the shaft 5 is 'a screw or bolt 69 that is suificiently long to engage against the end face of the shaft 5. The screw or bolt 69 is threaded in the cover 3 and by screwing it in the appropriate direction it forces the shaft 5 towards the cover plate 2. The force set up in the shaft 5, however, is transferred to the circlip 67 and thence to the sleeve 7 and rotor 6 via the thrust bearing 68. These members, in turn, transfer said vforce to the cylinder port plate 12 and the valve plate 20, the valve plate 20 being nonrotatably mounted on the shaft 5 by virtue of the fact that the key 21 also extends into a groove in the valve plate 20.

The cylinder port plate 12 and the valve plate 20 are thus maintained in close abutting relationship. The setting of the screw or nut 60 is held by a lock nut 70 and the shaft end in the boss 27 is formed with a groove 71 containing a sealing member 72.

The thrust plate 26 is supported by a thrust bearing 73 housed in a recess 74 in the boss 27, the thrust plate 26 having an annular projection 75 that extends into the inner periphery of the thrust hearing. A bearing sleeve 76 or a roller, ball, or needle bearing is accommodated between the annular projection 75 and the boss 27.

This construction, in operation, functions in the same manner as the embodiment described with reference to FIG. 2.

FIG. 4 is a cross-section of a further embodiment of the invention, in which means is provided for varying the output of the pump.

In this construction the laminated rotor 6 is again mounted on a sleeve 7, as in FIG. 3, the sleeve 7 being rotatably supported on the shaft 5 by needle bearings 8.

This construction, however, differs from that described with reference to FIG. 3 in that the boss 27 is now separate from, but rotatable on, the cover plate 3. To this end the boss 27 is formed with an annular projection 27A that is, or a plurality of spaced apart projections that are, a sliding fit in an annular groove 3A in the cover plate 3.

The boss 27 is a sliding fit on the shaft 5 but is secured against rotational movement thereon by a key 7 housed in grooves in the shaft 5 and the boss 27. The inclined face 27B of the boss is formed with an enlarged bore in which are housed one or more spring discs 78 as well as one end of a sleeve 79 extending between the spring discs 78 and the thrust bearing 68.

The shaft 5 extends through the cover plate 3 and includes circumferential groove in which is mounted a circlip 80, the circlip 80 being accommodated in an annular recess 31 in the inner face of the cover plate 3. The circlip 80 prevents the shaft 5 from being withdrawn outwardly of the cover plate 3.

When the cover plate 3 is secured in position by bolting it to the housing 1, the cover plate 3 exerts pressure on the boss 27 and this pressure is then transferred to the rotor 6 via the spring discs 78, the sleeve 79 and finally the thrust bearing 63 abutting one end of the sleeve 7. The resulting force, on the sleeve 7, maintains the rotating cylinder port plate 12 in engagement with the stationary valve plate 20.

The shaft end that extends from the cover plate 3 carries a key 82, the key 82 extending into a disc like member 83 that is concentric with the shaft and housed in a recess in the outer face of the cover plate 3. The shaft 5 is formed with a circumferential groove 84 accommodating a sealing member 85. Torsion spring 140 provides resilient biasing of shaft 5 against rotation.

The annular thrust plate 26, for the pistons 11, is illustrated as being part of the thrust bearing 73 housed in the recess 74 in the boss 27, the thrust plate 26 may be castellated to provide recesses 49, there being one recess for each piston 11 and into which recesses the ends of the pistons projecting from the rotor extend.

On rotation of the rotor 6, the pistons 11 are reciprocated in the sleeves by virtue of the fact that they are, as in the constructions described with reference to FIGS. 2 and 3, maintained in engagement with the inclined thrust plate 26 by the compression springs 50. The port plate 12 and the valve plate are as described with reference to FIG. 1 and function as already stated, except that the valve plate 20 is now held against rotation by one or more pins 86 in opposed bores in the boss 19 and the valve plate 20.

To vary the output of the unit, for a given speed of the rotor, the shaft 5 is given a turning movement to rotate the boss 27 relatively to the cover plate 3. Such a movement of the boss 27 causes the setting of the thrust plate 26 to be so positioned that a line joining its nearest and furthest points from the rotor 6 no longer lies on a line that is in line with, or substantially in line with, the centre line of the valve plate 20 passing through thetwo blank spaces or lands thereon. As a result, the output of the unit is reduced. By gradually increasing the angular displacement of the shaft 5 the output of the unit can be further reduced up to an angular displacement of 90 whereafter further displacement causes an increasing and reversed output of the unit.

Since the disc like member 83 is rotated with the shaft 5, the disc like member can carry or be engraved with a pointer co-operating with a scale on the cover plate 3.

It will be appreciated that the shaft 5 is rotatable only when constrained to do so by external means and that it is otherwise a non-rotating shaft around which the rotor rotates.

In addition, the pressure plate 26 and thrust bearing 73 may be as described with reference to FIG. 3.

This embodiment thus provides a means for providing a smooth control of the output of the unit, as well as means for reversing said output.

To prevent overloading of the fluid pressure developing unit, means may be included to automatically maintain the pressure output within a limited range. FIG. 5 is a schematic cross-section of such a unit.

In FIG. 5 the shaft 5 is held stationary against rotation by the previously described key 21 in the boss 19, the boss 19 supporting one end of said shaft. The other end of the shaft 5 is of increased diameter and acts as a housing for a cylindrical fitting 83, this enlarged end of the shaft 5 being supported in a boss 27 carried by the cover plate 3. g

The annular thrust plate 26, for the shoes 25, is carried by an annular member 89 formed with a pair of projections 90 extending one on each side of the shaft 5. A pivot 91, rigid with the projections 90, extends transversely through the shaft 5 such that the thrust plate 26 can pivot relatively to the shaft 5, and such that the thrust plate 26 is so positioned that a line joining its nearest and furthest points from the rotor 6 lies on a line that is in line with, or substantially in line with, the centre line passing through the two blank spaces or lands of the valve plate 20.

As in FIG. 1, a passage 36 connects the discharge port 23 with an annular cavity 35 in the boss 19, the annular cavity surrounding the end of the shaft 5 that is in the boss 19. The shaft 5 has a bore 33 along which fluid can flow from the annular cavity 35 to the bore in the shaft end containing the cylindrical fitting 88. The pivot pin 91 has a flow bore 92 such that the presence of the pivot pin 91 in the shaft 5 does not block the bore 33.

The boss 27 is formed with upper and lower bores 93, 94 respectively in which are housed upper and lower pistons 95, 96. Each piston carries, at one end, a ball 97 capable of engaging against the rear face of the annular member 89.

The upper piston has an outwardly flanged end 98 sliding in an enlarged portion 93A of the bore 93, the piston 95 being surrounded by a compression spring '99 acting at one end against said flanged end 98 and at its other end against the shoulder formed by the transition from the bore 93 to its enlarged portion 93A.

The piston 95 is formed with an axially extending blind bore 100 into which extends a cylindrical member 101,;

the cylindrical member 101 having a flanged end 102 acoommodated in a recess in an end cover 103 on the boss 27. The piston 95 is a sliding fit on the cylindrical member 101.

The enlarged end of the shaft 5 has a fluid flow passage 104 leading to a fluid flow passage 105 in the boss 27, the passage 105, in turn, leading to the enlarged por-. tion 93A of the bore 93. The flanged end 98 of the piston 95 is formed with a plurality of apertures 106 interconnecting the space between the flanges 98 and 102 with the enlarged portion 93A of the bore 93.

The cover 103 has a fluid flow port 107 that is aligned with an open ended bore 108 extending axially through the cylindrical member 101.

The lower piston 96 is formed with a blind bore 109 into which extends a cylindrical member 110' having a flanged end 111 that is accommodated in a recess in the end cover 103, the piston 96 being a sliding fit on the cylindrical member 110. A compression spring 112 surrounds the piston 96 and extends between the flanged end 111 of the cylindrical member 110 and an annular member 113 on the piston 96, the annular member 113 abutting against a circlip 114 on the piston 96.

The boss 27 is formed with passage 116 leading from the bore 94 to the inside of the unit as defined by the housing 1 and the cover plates 2, 3.

The cylindrical fitting 88, at the end facing the cover 103, is formed with a bore 117 housing a compression spring 118. The compression spring 118 biases a valve stem 119, extending through the innermost end of the cylindrical fitting 88, against the bore-33. When the valve stem 119 is biased against the bore 33 it permits a fluid flow path 120 leading from the bore 33 to flow passage 104. In this setting of the valve stem 119, it closes a flow path 121 leading via flow path 121A to an annular groove 122 surrounding the cylindrical fitting 88, this annular groove leading to a port 123 shown in broken lines. A fluid flow pipe, not shown, inter-connects the ports 123 and 107.

When the rotor 6 is stationary, the annular thrust plate 26 is maintained in the position illustrated by the compression spring 112 acting on the piston 96.

When the stator is energized, to cause rotation of the rotor 6, the pistons 11 are reciprocated for the reasons, and in the manner, already described with reference to FIG. 1 andthe resulting rise in fluid pressure in the discharge port 23 is transmitted via the passage 36, the annular cavity 35, and the bore 33 to the end of the valve stem 119. The pistons 11 continue to operate at their maximum amplitude of reciprocation until a predeter-,

mined pressure has been built up in the discharge port 23 so that said fluid pressure is transmitted via the flow path 120, the passages 104, 105, the enlarged bore 93A,

theflow apertures 106 in the flanged end 98 of the piston 95 to the space between the flanged end of the piston and the flanged end 102 of the cylindrical member 101. As

a result the piston 95 is biased towards the rotor 6 by virtue of the fact that the area of the flange 98 facing the flange 102 is greater than the area of the flange 98 acted on by the spring 99. This movement of the piston 95 causes the anular member 89, and thus the thrust plate 26, to pivot about the axis of the pivot 91, such a pivoting movement serving to reduce the throw of the pistons 11 and thus the volumetric output of the unit to prevent an excessive build up of pressure. If, for any reasons, the pressure should continue to rise the valve stem 119 will be forced further into the cylindrical. member 88 until it has been displaced sufficiently to expose the flow path 121. The fluid pressure is then transmitted via the flow path 121 and 121A, the annular groove 122, and the port 123 to the port 107 to act against the inner face of the piston 95 as defined by the blind bore 100. Thisextra thrust on the piston 95 causes it to move even further towards the rotor in a manner tilting the thrust plate 26 to such an extent that the throw of the pistons 11 is reduced to minimum flow conditions. The opening of the flow path 121 thus sets a limit to the pressure that can be generated by the unit to prevent it from being overloaded.

When the flow path 121 is closed, the valve stem 119 and the flow path 120 co-operate to act as a throttle for holding the pressure output and volumetric output of the unit within predetermined limits. Exhaust flow from passage 121 passes by recess in valve 119 to passage 121B into housing 1.

Although, once again, only one piston 11 has been illustrated in FIG. it is to be understood that this is for reasons of clarity only and that there are in fact a plurality of such pistons as described with reference to FIG. 1.

The stator 4 may be of any conventional construction such as for example, the laminated type having slots or grooves therein and wound with insulated windings to produce the necessary magnetic field for causing rotation of the rotor.

The remaining parts of the particular embodiment illustrated in FIG. 5, that are identified by reference numerals already used for corresponding parts in FIGS. 1 to 4, are the same as, and operate in the same manner as, said corresponding parts.

The sleeves 10, instead of being mounted in bores in the laminations of the rotor, can be replaced by single drum containing a plurality of bores acting as cylinders for the pistons, the drum being inserted in the rotor and held against rotation therein as illustrated in FIG. 6.

In the embodiment illustrated in FIG. 6, a cylinder block drum 175, formed with parallel or substantially parallel bores 9, extends into one end of the sleeve 7 of the rotor 6. Extending into the other end of the sleeve 7 is a valve block 196, the valve block 196 being provided with an inlet port 211 and an outlet port 23, and has a key or pin 197 that locks the block 196 against rotation relatively to the end cover 2.

Endwise movement of the valve block 196 is restrained by a retaining ring 198 which is positioned in an annular groove in the end cover 2 and is subject to engagement with and force from an angular surface 196A. If desired cover 2 and valve block 196 can be combined to form a one piece member.

Between the valve block 196 and the cylinder block drum 175 is a valve plate 20", the valve plate 20" being made stationary with respect to the valve block 196 by brazing thereto, or by a similar method, or it may be pinned to prevent rotation. The valve plate 20 is formed with ports 22 similar to those described with reference to FIG. 1.

The sleeve 7 is formed with a shoulder 7 that abuts against the rotor 6 at its right hand end, as viewed in the figure, and a key 176, fitting in a keyway 177 in the cylinder block drum 175 as well as in a slot 179 in the sleeve 7 and in a keyway 178 in the rotor 6, locks the rotor 6, the sleeve 7 and the cylinder block drum 175 together against relative rotation with respect to each other.

Mounted on the right hand end of the sleeve 7, as viewed in the drawing, is a bearing race 193 housed within a cylindrically shaped projection 192 of the end cover 3,

there being a spacer ring 195 between the bearing race 193 and the rotor 6, and la circlip 194 in a groove in the sleeve 7 to retain the bearing race 193 on the sleeve.

Mounted on the left hand end of the sleeve 7 is a bearing race 204 held against removal therefrom by a circlip 205 in a groove in the sleeve 7. A spacer ring 206 is-positioned between the rotor 6 and the bearing race 204. The bearing race 204 is housed within a cylindrical bore in a boss 19 extending axially inwardly from the cover plate 2.

The rotor 6, sleeve 7 and cylinder block drum are thus rotatably mounted within the housing 1.

The bores 9 in the cylinder block drum 175 are disposed and arranged as described with reference to FIG. 1.

Within each bore 9, or a sleeve therein, is a piston 11, each piston having 'a head associated with a shoe 25 sliding on a thrust plate 184, each piston having an axial bore extending therethrough and communicating with an orifice and a circular recess in its associated shoe 25, all as described with reference to FIG. 1. Each bore 9, at its left hand end, communicates with an arcuate shaped port 18 via an opening 17, the ports 18 being so disposed that they are rotatable relatively to the valve plate 20" while in communication with the ports 22 in the valve plate 20".

The cylinder block drum 175 is formed with an axial bore or chamber 202 having a reduced axial passage 212A at its left hand end, the passage 212A leading to a recess 212 in the valve plate 20". The recess 212 leads to a passage 201 in the valve plate 20", this passage 201 being in communication with a passage 200 in the valve block 196 leading to the outlet port 23. A plug 203, where shown, blocks an aperture created during the formation of the passage 200.

Within the chamber 202 is a compression spring acting on the left hand end of chamber thus biassing cylinder block 175 against valve plate 20 also on a thrust rod 181 slidable in the chamber 202, the thrust rod 181 having an outer spherical end swaged into a retainer plate 182. The thrust rod 181 is formed with an axial passage 213 extending therethrough and leading to bores 214, 215 in the retainer plate 182.

A boss 182A, on the retainer plate 182, is formed with axial serrations 183 slidably mounted in interlocking serrations 183A in the thrust plate 184 which is mounted in a thrust bearing 185. The thrust plate 184 has a central bore therein in which is housed a plug 186 abutting the sernations 183A, the plug 186 having a boss extending to a limited extent into a bore in the retainer plate 182 so as to leave a chamber 216 in said bore communicating with the bore 215. The plug 186 is itself formed with a through bore 217 leading to chamber 216.

The thrust bearing is housed in a yoke mounted on trunnion bearings, the two diametrically opposed pintles 191 of which (only one is shown) are mounted in the projections 192 of the end cover 3. The yoke 190 is mounted on a yoke pin 188 extending through a curved thrust washer 189 on the right hand face of the yoke, the pin 188 having a flange 188A that is housed in a recess in the yoke 190 and held therein by the curved thrust washer 189. A chamber 218 exists between the plug 186 and the yoke pin 188. The curved thrust washer 189 abuts against a curved surface 208B of an end member 208 secured to the end cover 3 by screws or similar means not shown, the end member 208 having a slot 208A providing a path for the yoke pin 188.

The yoke pin 188 is aligned with the central bore in the thrust plate 184, and the pin 188 has a through bore permitting fluid pressure in this central bore to be transmitted to a spherical end 220 of the yoke pin, said spherical end 220 being mounted in a pin 207A. Groove 188C is to provide a pressurised area between yoke pin 188 and thrust plate 184. The pin 207A is slidable in a chamber 207B in a spool 207, the spool 207 being accommodated in an end body 209 attached to the end cover 3.

As illustrated the thrust plate 184 is at a maximum inclination to the longitudinal axis of the rotor 6 since the yoke 190 is in engagement with an upper pad 219 in the cylindrically shaped projection. By suitably operating the spool 207 the chamber 2073 can be displaced down- Wardly to lower the pin 188 and thereby reduce the angle of inclination of the thrust plate 184. Such movement can be continued until the thrust plate 184 is normal to the axis of the rotor 6 and then beyond such a setting until the yoke 190 engages a lower pad 219 in the cylindrical housing, this setting representing the maximum inclination of the thrust plate 184 in the opposite direction. This means for varying the inclination of the thrust plate 184 is representative of only one of numerous types of similar controls and is not intended to be a limitative means.

Seals 42, 187, 199 and 210 are provided, where shown,

for sealing purposes.

When the windings in the stator 4 are suitably energized the rotor 6 is rotate-d and through the. key 176 causes the cylinder block 175 to rotate with it. While the pressure is building up the spring 180, acting on the thrust rod 181 and thus on the retainer plate 182, maintains the shoes 25 in engagement with the tilted thrust plate 184 and, in consequence the pistons 11 are reciprocated to build up a pressure in the manner described with reference to FIG. 1 with the exception that thrust plate 184 will rotate in unison with retainer plate 182 owing to the mating serrations 183 and 183A.

Pressure generated in the outlet port 23 is transmitted via passages 200, 201, chamber 212, passage 212A to chamber 202 thereby applying pressure to end surfaces and the like of the thrust rod 181 to supplement the force of the spring 180 on the thrust rod 181, the combined forces being applied to the retainer plate 182.

Fluid passing through passage 214, 215, chamber 216, passage 217, chamber 218 and passage 1888 will cause back pressure to react in chamber 218 thus forcing flange 183A against the thrust washer 189 into abutment with curved surface 208B, force will also be applied to surface of plug 186 which being in abutment with end surfaces of serrations 183A thereby tending to separate the thrust plate 184 from the thrust bearing 185 thus reducing the load on the bearing 185 and pintle pins 191. Pressure in chamber 216 will oppose the pressure chamber 202 thus reducing the load on the retaining plate 182, and thrust plate 184.

It will be appreciated that when the yoke 190 is moved from the position shown to a position where the face of thrust plate 184 is at 90 from the axis of the cylinder block, flow will be reduced to zero volume. Should reverse flow be desired passage 200 may not be required in which event pressurized fluid may be conducted via spool 207, chamber 207B, passage provided in pin 207A to passage 188B.

It will be appreciated that the present invention is capable of many modifications as is evidenced by the various constructions described above and it is the intention that the above described embodiments shall not be regarded as being in any way limitative and that the invention covers all those various embodiments as may fall within the scope of the appended claims.

What I claim is:

1. A pressure developing unit comprising an electric motor, said electric motor including a stator and a rotor, a plurality of bores in the rotor equally spaced from the axis of rotation of the rotor and extending parallel thereto, a tubular sleeve in each of said bores, a piston in each sleeve, each piston having one end projecting from one end of its associated sleeve, a thrust plate, means maintaining said projecting end of each piston in sliding relationship with said thrust plate, means for supporting said thrust plate in inclined relationship relative to the axis of rotation of the rotor whereby as the rotor rotates the pistons are caused to reciprocate in their sleeves, at least one end of each sleeve extending out of said rotor and into a fluid flow opening extending through a port plate, said port plate being rotatable with said rotor,

12 means for effecting limited axial and inclined motion of said port plate relative to said rotor and said sleeves, said last-mentioned means including sealing means between said sleeves and the fluid flow openings in the port plate thereby forming a liquid tight seal in addition to effecting the latter-noted relatve axial and inclined motion.

2. The pressure developng unit as defined in claim 1 wherein said rotor is of a laminated construction.

3. The pressure developing unit as defined in claim 1 including means for selectively placing said sleeves in fluid communication with fluid ports whereby upon energization of the electric motor fluid flow occurs through said fluid ports under the influence of piston-movement in the sleeves, said last-mentioned means including a valve plate, said port plate being positioned between said valve plate and said rotor, the valve plate having a pair of arcuate shaped ports, one of said arcuate shaped ports being in communication with one of said first-mentioned fluid ports and another of said arcuate shaped ports being in fluid communication with another of said first-mentioned fluid ports.

4. The pressure developing unit as defined in claim 1 including a pressure plate, said rotor being positioned between said thrust plate and said pressure plate, an outlet port, and means placing the outlet port in fluid communication with said pressure plate whereby said pressure plate is biased by fluid against said rotor 5. The pressure developing unit as defined in claim 1 including a non-rotatable shaft, said rotor being rotatable relative to said shaft, a pressure plate mounted on said shaft, said rotor being positioned between said pressure plate and said thrust plate, a portion of said pressure plate defining a fluid chamber, an outlet, and passage means between said outlet and said fluid chamber whereby pressurized fluid from said outlet is communicated to' said chamber for biasing said pressure plate against said rotor.

6. The pressure develping unit as defined in claim 1 including means for etfecting the automatic tilting of the thrust plate about an axis generally normal to the rotor axis whereby excessive pressure buildup in said unit is precluded.

7. The pressure developing unit as defined in claim 1 including means for tilting said thrust plate about an axis generally normal to the rotor axis to prevent excessive pressure buildup in said unit, said last mentioned means including spring means biasing the thrust plate to a position effecting maximum piston stroke upon initial energization of said unit whereby said unit operates at maximum output upon such initial energization, and said tilting means includes piston and cylinder means operative against said thrust plate to decrease the tilt-angle thereof in response to the output fluid pressure of said unit, whereby inclination of said thrust plate is reduced upon output pressure build-up to prevent excessive pressure build-up in said unit.

8. The pressure developing unit as defined in claim 1 wherein an opposite end of each sleeve extends out of said rotor in an opposite direction to said one end of said sleeves, a pressure plate, said rotor being positioned between said pressure plate and said port plate, and said last-mentioned sleeve ends being received in recesses of said pressure plate.

9. The pressure developing unit as defined in claim 1, wherein each fluid flow opening is defined by a cylindrical bore telescopically receiving an assocated one of each of said sleeve ends, and said sealing means is an angular seal between each sleeve end and said cylindrical bore.

References Cited by the Examiner UNITED STATES PATENTS (Other references on following page) 13 UNITED STATES PATENTS Ferris 103-152 Michie et a1. 103118 Lundgren 103-162 Budzich 103-l62 Kececioglu et a1 103118 Garnier 103162 Firth et a1. 103162 3,139,037 6/1964 Budzich 103-162 3,175,510 3/1965 DAmato 103162 3,191,543 6/1965 Harm et a1. 103-162 5 MARK NEWMAN, Primary Examiner.

SAMUEL LEVINE, Examiner.

R. M. VARGO, Assistant Examiner. 

1. A PRESSURE DEVELOPING UNIT COMPRISING AN ELECTRIC MOTOR, SAID ELECTRIC MOTOR INCLUDING A STATOR AND A ROTOR, A PLURALITY OF BORES IN THE ROTOR EQUALLY SPACED FROM THE AXIS OF ROTATION OF THE ROTOR AND EXTENDING PARALLEL THERETO, A TUBULAR SLEEVE IN EACH OF SAID BORES, A PISTON IN EACH SLEEVE, EACH PISTON HAVING ONE END PROJECTING FROM ONE END OF ITS ASSOCIATED SLEEVE, A THRUST PLATE, MEANS MAINTAINING SAID PROJECTING END OF EACH PISTON IN SLIDING RELATIONSHIP WITH SAID THRUST PLATE, MEANS FOR SUPPORTING SAID THRUST PLATE IN INCLINED RELATIONSHIP RELATIVE TO THE AXIS OF ROTATION OF THE ROTOR WHEREBY AS THE ROTOR ROTATES THE PISTONS ARE CAUSED TO RECIPROCATE IN THEIR SLEEVES, AT LEAST ONE END OF EACH SLEEVE EXTENDING OUT OF SAID ROTOR AND INTO A FLUID FLOW OPENING EXTENDING THROUGH A PORT PLATE, SAID PORT PLATE BEING ROTATABLE WITH SAID ROTOR, MEANS FOR EFFECTING LIMITED AXIAL AND INCLINED MOTION OF SAID PORT PLATE RELATIVE TO SAID ROTOR AND SAID SLEEVES, SAID LAST-MENTIONED MEANS INCLUDING SEALING MEANS BETWEEN SAID SLEEVES AND THE FLUID FLOW OPENINGS IN THE PORT PLATE THEREBY FORMING A LIQUID TIGHT SEAL IN ADDITION TO EFFECTING THE LATTER-NOTED RELATIVE AXIAL AND INCLINED MOTION. 